[RFC PATCH] powerpc/ftrace: Refactoring and support for -fpatchable-function-entry
Naveen N Rao
naveen at kernel.org
Sun May 21 04:28:01 AEST 2023
Christophe Leroy wrote:
>
>
> Le 19/05/2023 à 21:26, Naveen N Rao a écrit :
>> [Vous ne recevez pas souvent de courriers de naveen at kernel.org. Découvrez pourquoi ceci est important à https://aka.ms/LearnAboutSenderIdentification ]
>>
>> Refactor ftrace code and move to using ftrace_replace_code() to help
>> simplify and make the code more maintainable.
>>
>> - The existing ftrace.c code is moved to a separate file so that ppc64
>> elfv1 and clang -pg only support continue. This makes it possible to
>> converge ppc32 and ppc64 support further.
>> - Drop code to re-purpose compiler-generated long branches for ftrace
>> use in support of large kernels. We still retain the ftrace stubs at
>> the end of .text, so we now support kernels upto ~64MB.
>> - Add ftrace_init_nop() to keep boot-time validations and init separate
>> from runtime.
>> - Implement ftrace_replace_code() to simplify overall ftrace setup. This
>> will be especially useful when adding ability to nop out 'mflr r0'
>> later, and for other subsequent ftrace features.
>> - Add support for -fpatchable-function-entry. On ppc64, this needs gcc
>> v13.1 so that the nops are generated at LEP. This also moves ppc32 to
>> using the same two-instruction sequence as that of ppc64.
>>
>> This applies atop patches 1-3 of Nick's series for elfv2 conversion, as
>> well as Nick's patch enabling -mprofile-kernel for elfv2 BE:
>> - https://lore.kernel.org/all/20230505071850.228734-1-npiggin@gmail.com/
>> - https://lore.kernel.org/all/20230506011814.8766-1-npiggin@gmail.com/
>>
>> This builds for me and passes a quick test, posting this as an early
>> RFC.
>>
>> Signed-off-by: Naveen N Rao <naveen at kernel.org>
>
> Looks good, works on PPC32 but I observed some performance degradation,
> around 25% more time needed to activate function tracer and around 10%
> more time needed to de-activate function tracer (by writting
> function/nop into /sys/kernel/debug/tracing/current_tracer.
>
> Note that the trampoline at end of .text is only on PPC64 at the moment,
> so if PPC32 kernel goes beyond 32M we will have a problem (it happens
> with allyesconfig). It should be easy to extend it to PPC32.
Indeed, let me make that change.
>
> At the begining of ftrace_replace_code(), don't you miss:
>
> if (unlikely(ftrace_disabled))
> return;
ftrace_disabled is a static, so it can't be tested here. FWIW, x86 also
implements ftrace_replace_code(), and doesn't test ftrace_disabled.
Looking at the call path, it looks like it gets tested much before, so
may not be necessary. It sure would be good to get Steven's view on
this.
>
> Below fix needed in order to build:
>
> diff --git a/arch/powerpc/kernel/trace/ftrace.c
> b/arch/powerpc/kernel/trace/ftrace.c
> index a9d57f338bd7..81d5bd69b660 100644
> --- a/arch/powerpc/kernel/trace/ftrace.c
> +++ b/arch/powerpc/kernel/trace/ftrace.c
> @@ -96,7 +96,6 @@ static unsigned long find_ftrace_tramp(unsigned long ip)
>
> static int ftrace_get_call_inst(struct dyn_ftrace *rec, unsigned long
> addr, ppc_inst_t *call_inst)
> {
> - struct module *mod = rec->arch.mod;
> unsigned long ip = rec->ip;
> unsigned long stub;
>
> @@ -112,7 +111,11 @@ static int ftrace_get_call_inst(struct dyn_ftrace
> *rec, unsigned long addr, ppc_
> }
> } else if (IS_ENABLED(CONFIG_MODULES)) {
> /* Module code would be going to one of the module stubs */
> +#ifdef CONFIG_MODULES
> + struct module *mod = rec->arch.mod;
> +
> stub = (addr == (unsigned long)ftrace_caller ? mod->arch.tramp :
> mod->arch.tramp_regs);
> +#endif
> } else {
> return -EINVAL;
> }
Thanks! I'll fold this in.
- Naveen
>
>
> Christophe
>
>> ---
>> arch/powerpc/Kconfig | 10 +
>> arch/powerpc/Makefile | 5 +
>> arch/powerpc/include/asm/ftrace.h | 10 +-
>> arch/powerpc/include/asm/module.h | 4 -
>> arch/powerpc/kernel/trace/Makefile | 8 +-
>> arch/powerpc/kernel/trace/ftrace.c | 816 +++++------------
>> arch/powerpc/kernel/trace/ftrace_pg.c | 846 ++++++++++++++++++
>> .../gcc-check-fpatchable-function-entry.sh | 20 +
>> 8 files changed, 1106 insertions(+), 613 deletions(-)
>> create mode 100644 arch/powerpc/kernel/trace/ftrace_pg.c
>> create mode 100755 arch/powerpc/tools/gcc-check-fpatchable-function-entry.sh
>>
>> diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig
>> index 902b6b99f7ecd5..6db94723af7d30 100644
>> --- a/arch/powerpc/Kconfig
>> +++ b/arch/powerpc/Kconfig
>> @@ -187,6 +187,7 @@ config PPC
>> select DYNAMIC_FTRACE if FUNCTION_TRACER
>> select EDAC_ATOMIC_SCRUB
>> select EDAC_SUPPORT
>> + select FTRACE_MCOUNT_USE_PATCHABLE_FUNCTION_ENTRY if ARCH_USING_PATCHABLE_FUNCTION_ENTRY
>> select GENERIC_ATOMIC64 if PPC32
>> select GENERIC_CLOCKEVENTS_BROADCAST if SMP
>> select GENERIC_CMOS_UPDATE
>> @@ -552,6 +553,15 @@ config MPROFILE_KERNEL
>> def_bool $(success,$(srctree)/arch/powerpc/tools/gcc-check-mprofile-kernel.sh $(CC) -mlittle-endian) if CPU_LITTLE_ENDIAN
>> def_bool $(success,$(srctree)/arch/powerpc/tools/gcc-check-mprofile-kernel.sh $(CC) -mbig-endian) if CPU_BIG_ENDIAN
>>
>> +config ARCH_HAS_PATCHABLE_FUNCTION_ENTRY_AT_LEP
>> + depends on PPC64_ELF_ABI_V2 && FUNCTION_TRACER
>> + def_bool $(success,$(srctree)/arch/powerpc/tools/gcc-check-fpatchable-function-entry.sh $(CC) -mlittle-endian) if CPU_LITTLE_ENDIAN
>> + def_bool $(success,$(srctree)/arch/powerpc/tools/gcc-check-fpatchable-function-entry.sh $(CC) -mbig-endian) if CPU_BIG_ENDIAN
>> +
>> +config ARCH_USING_PATCHABLE_FUNCTION_ENTRY
>> + depends on FUNCTION_TRACER && (PPC32 || PPC64_ELF_ABI_V2)
>> + def_bool ARCH_HAS_PATCHABLE_FUNCTION_ENTRY_AT_LEP || (PPC32 && $(cc-option, -fpatchable-function-entry=2))
>> +
>> config HOTPLUG_CPU
>> bool "Support for enabling/disabling CPUs"
>> depends on SMP && (PPC_PSERIES || \
>> diff --git a/arch/powerpc/Makefile b/arch/powerpc/Makefile
>> index dca73f673d7046..de39478b1c9e9f 100644
>> --- a/arch/powerpc/Makefile
>> +++ b/arch/powerpc/Makefile
>> @@ -148,11 +148,16 @@ CFLAGS-$(CONFIG_PPC32) += $(call cc-option, $(MULTIPLEWORD))
>> CFLAGS-$(CONFIG_PPC32) += $(call cc-option,-mno-readonly-in-sdata)
>>
>> ifdef CONFIG_FUNCTION_TRACER
>> +ifdef CONFIG_ARCH_USING_PATCHABLE_FUNCTION_ENTRY
>> +KBUILD_CPPFLAGS += -DCC_USING_PATCHABLE_FUNCTION_ENTRY
>> +CC_FLAGS_FTRACE := -fpatchable-function-entry=2
>> +else
>> CC_FLAGS_FTRACE := -pg
>> ifdef CONFIG_MPROFILE_KERNEL
>> CC_FLAGS_FTRACE += -mprofile-kernel
>> endif
>> endif
>> +endif
>>
>> CFLAGS-$(CONFIG_TARGET_CPU_BOOL) += -mcpu=$(CONFIG_TARGET_CPU)
>> AFLAGS-$(CONFIG_TARGET_CPU_BOOL) += -mcpu=$(CONFIG_TARGET_CPU)
>> diff --git a/arch/powerpc/include/asm/ftrace.h b/arch/powerpc/include/asm/ftrace.h
>> index 91c049d51d0e10..d1a16543a37b00 100644
>> --- a/arch/powerpc/include/asm/ftrace.h
>> +++ b/arch/powerpc/include/asm/ftrace.h
>> @@ -22,18 +22,26 @@ extern void _mcount(void);
>>
>> static inline unsigned long ftrace_call_adjust(unsigned long addr)
>> {
>> - /* relocation of mcount call site is the same as the address */
>> + if (IS_ENABLED(CONFIG_ARCH_USING_PATCHABLE_FUNCTION_ENTRY))
>> + addr += MCOUNT_INSN_SIZE;
>> +
>> return addr;
>> }
>>
>> unsigned long prepare_ftrace_return(unsigned long parent, unsigned long ip,
>> unsigned long sp);
>>
>> +struct module;
>> +struct dyn_ftrace;
>> struct dyn_arch_ftrace {
>> struct module *mod;
>> };
>>
>> #ifdef CONFIG_DYNAMIC_FTRACE_WITH_ARGS
>> +#define ftrace_need_init_nop() (true)
>> +int ftrace_init_nop(struct module *mod, struct dyn_ftrace *rec);
>> +#define ftrace_init_nop ftrace_init_nop
>> +
>> struct ftrace_regs {
>> struct pt_regs regs;
>> };
>> diff --git a/arch/powerpc/include/asm/module.h b/arch/powerpc/include/asm/module.h
>> index ac53606c259430..a8e2e8339fb7f4 100644
>> --- a/arch/powerpc/include/asm/module.h
>> +++ b/arch/powerpc/include/asm/module.h
>> @@ -75,10 +75,6 @@ struct mod_arch_specific {
>> #endif
>>
>> #ifdef CONFIG_DYNAMIC_FTRACE
>> -# ifdef MODULE
>> - asm(".section .ftrace.tramp,\"ax\", at nobits; .align 3; .previous");
>> -# endif /* MODULE */
>> -
>> int module_trampoline_target(struct module *mod, unsigned long trampoline,
>> unsigned long *target);
>> int module_finalize_ftrace(struct module *mod, const Elf_Shdr *sechdrs);
>> diff --git a/arch/powerpc/kernel/trace/Makefile b/arch/powerpc/kernel/trace/Makefile
>> index b16a9f9c0b35f2..2296bbbd775ac8 100644
>> --- a/arch/powerpc/kernel/trace/Makefile
>> +++ b/arch/powerpc/kernel/trace/Makefile
>> @@ -8,13 +8,13 @@ ifdef CONFIG_FUNCTION_TRACER
>> CFLAGS_REMOVE_ftrace.o = $(CC_FLAGS_FTRACE)
>> endif
>>
>> -obj32-$(CONFIG_FUNCTION_TRACER) += ftrace_mprofile.o
>> +obj32-$(CONFIG_FUNCTION_TRACER) += ftrace_mprofile.o ftrace.o
>> ifdef CONFIG_MPROFILE_KERNEL
>> -obj64-$(CONFIG_FUNCTION_TRACER) += ftrace_mprofile.o
>> +obj64-$(CONFIG_FUNCTION_TRACER) += ftrace_mprofile.o ftrace.o
>> else
>> -obj64-$(CONFIG_FUNCTION_TRACER) += ftrace_64_pg.o
>> +obj64-$(CONFIG_FUNCTION_TRACER) += ftrace_64_pg.o ftrace_pg.o
>> endif
>> -obj-$(CONFIG_FUNCTION_TRACER) += ftrace_low.o ftrace.o
>> +obj-$(CONFIG_FUNCTION_TRACER) += ftrace_low.o
>> obj-$(CONFIG_TRACING) += trace_clock.o
>>
>> obj-$(CONFIG_PPC64) += $(obj64-y)
>> diff --git a/arch/powerpc/kernel/trace/ftrace.c b/arch/powerpc/kernel/trace/ftrace.c
>> index a47f303734233b..a9d57f338bd78e 100644
>> --- a/arch/powerpc/kernel/trace/ftrace.c
>> +++ b/arch/powerpc/kernel/trace/ftrace.c
>> @@ -28,64 +28,52 @@
>> #include <asm/syscall.h>
>> #include <asm/inst.h>
>>
>> -/*
>> - * We generally only have a single long_branch tramp and at most 2 or 3 plt
>> - * tramps generated. But, we don't use the plt tramps currently. We also allot
>> - * 2 tramps after .text and .init.text. So, we only end up with around 3 usable
>> - * tramps in total. Set aside 8 just to be sure.
>> - */
>> -#define NUM_FTRACE_TRAMPS 8
>> +#define NUM_FTRACE_TRAMPS 2
>> static unsigned long ftrace_tramps[NUM_FTRACE_TRAMPS];
>>
>> -static ppc_inst_t
>> -ftrace_call_replace(unsigned long ip, unsigned long addr, int link)
>> +static ppc_inst_t ftrace_create_branch_inst(unsigned long ip, unsigned long addr, int link)
>> {
>> ppc_inst_t op;
>>
>> - addr = ppc_function_entry((void *)addr);
>> -
>> - /* if (link) set op to 'bl' else 'b' */
>> + WARN_ON(!is_offset_in_branch_range(addr - ip));
>> create_branch(&op, (u32 *)ip, addr, link ? BRANCH_SET_LINK : 0);
>>
>> return op;
>> }
>>
>> -static inline int
>> -ftrace_modify_code(unsigned long ip, ppc_inst_t old, ppc_inst_t new)
>> +static inline int ftrace_read_inst(unsigned long ip, ppc_inst_t *op)
>> {
>> - ppc_inst_t replaced;
>> -
>> - /*
>> - * Note:
>> - * We are paranoid about modifying text, as if a bug was to happen, it
>> - * could cause us to read or write to someplace that could cause harm.
>> - * Carefully read and modify the code with probe_kernel_*(), and make
>> - * sure what we read is what we expected it to be before modifying it.
>> - */
>> -
>> - /* read the text we want to modify */
>> - if (copy_inst_from_kernel_nofault(&replaced, (void *)ip))
>> + if (copy_inst_from_kernel_nofault(op, (void *)ip)) {
>> + pr_err("0x%lx: fetching instruction failed\n", ip);
>> return -EFAULT;
>> -
>> - /* Make sure it is what we expect it to be */
>> - if (!ppc_inst_equal(replaced, old)) {
>> - pr_err("%p: replaced (%08lx) != old (%08lx)", (void *)ip,
>> - ppc_inst_as_ulong(replaced), ppc_inst_as_ulong(old));
>> - return -EINVAL;
>> }
>>
>> - /* replace the text with the new text */
>> - return patch_instruction((u32 *)ip, new);
>> + return 0;
>> }
>>
>> -/*
>> - * Helper functions that are the same for both PPC64 and PPC32.
>> - */
>> -static int test_24bit_addr(unsigned long ip, unsigned long addr)
>> +static inline int ftrace_validate_inst(unsigned long ip, ppc_inst_t inst)
>> {
>> - addr = ppc_function_entry((void *)addr);
>> + ppc_inst_t op;
>> + int ret;
>>
>> - return is_offset_in_branch_range(addr - ip);
>> + ret = ftrace_read_inst(ip, &op);
>> + if (!ret && !ppc_inst_equal(op, inst)) {
>> + pr_err("0x%lx: expected (%08lx) != found (%08lx)\n",
>> + ip, ppc_inst_as_ulong(inst), ppc_inst_as_ulong(op));
>> + ret = -EINVAL;
>> + }
>> +
>> + return ret;
>> +}
>> +
>> +static inline int ftrace_modify_code(unsigned long ip, ppc_inst_t old, ppc_inst_t new)
>> +{
>> + int ret = ftrace_validate_inst(ip, old);
>> +
>> + if (!ret)
>> + ret = patch_instruction((u32 *)ip, new);
>> +
>> + return ret;
>> }
>>
>> static int is_bl_op(ppc_inst_t op)
>> @@ -93,138 +81,11 @@ static int is_bl_op(ppc_inst_t op)
>> return (ppc_inst_val(op) & ~PPC_LI_MASK) == PPC_RAW_BL(0);
>> }
>>
>> -static int is_b_op(ppc_inst_t op)
>> -{
>> - return (ppc_inst_val(op) & ~PPC_LI_MASK) == PPC_RAW_BRANCH(0);
>> -}
>> -
>> -static unsigned long find_bl_target(unsigned long ip, ppc_inst_t op)
>> -{
>> - int offset;
>> -
>> - offset = PPC_LI(ppc_inst_val(op));
>> - /* make it signed */
>> - if (offset & 0x02000000)
>> - offset |= 0xfe000000;
>> -
>> - return ip + (long)offset;
>> -}
>> -
>> -#ifdef CONFIG_MODULES
>> -static int
>> -__ftrace_make_nop(struct module *mod,
>> - struct dyn_ftrace *rec, unsigned long addr)
>> -{
>> - unsigned long entry, ptr, tramp;
>> - unsigned long ip = rec->ip;
>> - ppc_inst_t op, pop;
>> -
>> - /* read where this goes */
>> - if (copy_inst_from_kernel_nofault(&op, (void *)ip)) {
>> - pr_err("Fetching opcode failed.\n");
>> - return -EFAULT;
>> - }
>> -
>> - /* Make sure that this is still a 24bit jump */
>> - if (!is_bl_op(op)) {
>> - pr_err("Not expected bl: opcode is %08lx\n", ppc_inst_as_ulong(op));
>> - return -EINVAL;
>> - }
>> -
>> - /* lets find where the pointer goes */
>> - tramp = find_bl_target(ip, op);
>> -
>> - pr_devel("ip:%lx jumps to %lx", ip, tramp);
>> -
>> - if (module_trampoline_target(mod, tramp, &ptr)) {
>> - pr_err("Failed to get trampoline target\n");
>> - return -EFAULT;
>> - }
>> -
>> - pr_devel("trampoline target %lx", ptr);
>> -
>> - entry = ppc_global_function_entry((void *)addr);
>> - /* This should match what was called */
>> - if (ptr != entry) {
>> - pr_err("addr %lx does not match expected %lx\n", ptr, entry);
>> - return -EINVAL;
>> - }
>> -
>> - if (IS_ENABLED(CONFIG_MPROFILE_KERNEL)) {
>> - if (copy_inst_from_kernel_nofault(&op, (void *)(ip - 4))) {
>> - pr_err("Fetching instruction at %lx failed.\n", ip - 4);
>> - return -EFAULT;
>> - }
>> -
>> - /* We expect either a mflr r0, or a std r0, LRSAVE(r1) */
>> - if (!ppc_inst_equal(op, ppc_inst(PPC_RAW_MFLR(_R0))) &&
>> - !ppc_inst_equal(op, ppc_inst(PPC_INST_STD_LR))) {
>> - pr_err("Unexpected instruction %08lx around bl _mcount\n",
>> - ppc_inst_as_ulong(op));
>> - return -EINVAL;
>> - }
>> - } else if (IS_ENABLED(CONFIG_PPC64)) {
>> - /*
>> - * Check what is in the next instruction. We can see ld r2,40(r1), but
>> - * on first pass after boot we will see mflr r0.
>> - */
>> - if (copy_inst_from_kernel_nofault(&op, (void *)(ip + 4))) {
>> - pr_err("Fetching op failed.\n");
>> - return -EFAULT;
>> - }
>> -
>> - if (!ppc_inst_equal(op, ppc_inst(PPC_INST_LD_TOC))) {
>> - pr_err("Expected %08lx found %08lx\n", PPC_INST_LD_TOC,
>> - ppc_inst_as_ulong(op));
>> - return -EINVAL;
>> - }
>> - }
>> -
>> - /*
>> - * When using -mprofile-kernel or PPC32 there is no load to jump over.
>> - *
>> - * Otherwise our original call site looks like:
>> - *
>> - * bl <tramp>
>> - * ld r2,XX(r1)
>> - *
>> - * Milton Miller pointed out that we can not simply nop the branch.
>> - * If a task was preempted when calling a trace function, the nops
>> - * will remove the way to restore the TOC in r2 and the r2 TOC will
>> - * get corrupted.
>> - *
>> - * Use a b +8 to jump over the load.
>> - * XXX: could make PCREL depend on MPROFILE_KERNEL
>> - * XXX: check PCREL && MPROFILE_KERNEL calling sequence
>> - */
>> - if (IS_ENABLED(CONFIG_MPROFILE_KERNEL) || IS_ENABLED(CONFIG_PPC32))
>> - pop = ppc_inst(PPC_RAW_NOP());
>> - else
>> - pop = ppc_inst(PPC_RAW_BRANCH(8)); /* b +8 */
>> -
>> - if (patch_instruction((u32 *)ip, pop)) {
>> - pr_err("Patching NOP failed.\n");
>> - return -EPERM;
>> - }
>> -
>> - return 0;
>> -}
>> -#else
>> -static int __ftrace_make_nop(struct module *mod, struct dyn_ftrace *rec, unsigned long addr)
>> -{
>> - return 0;
>> -}
>> -#endif /* CONFIG_MODULES */
>> -
>> static unsigned long find_ftrace_tramp(unsigned long ip)
>> {
>> int i;
>>
>> - /*
>> - * We have the compiler generated long_branch tramps at the end
>> - * and we prefer those
>> - */
>> - for (i = NUM_FTRACE_TRAMPS - 1; i >= 0; i--)
>> + for (i = 0; i < NUM_FTRACE_TRAMPS; i++)
>> if (!ftrace_tramps[i])
>> continue;
>> else if (is_offset_in_branch_range(ftrace_tramps[i] - ip))
>> @@ -233,449 +94,200 @@ static unsigned long find_ftrace_tramp(unsigned long ip)
>> return 0;
>> }
>>
>> -static int add_ftrace_tramp(unsigned long tramp)
>> +static int ftrace_get_call_inst(struct dyn_ftrace *rec, unsigned long addr, ppc_inst_t *call_inst)
>> {
>> - int i;
>> -
>> - for (i = 0; i < NUM_FTRACE_TRAMPS; i++)
>> - if (!ftrace_tramps[i]) {
>> - ftrace_tramps[i] = tramp;
>> - return 0;
>> - }
>> -
>> - return -1;
>> -}
>> -
>> -/*
>> - * If this is a compiler generated long_branch trampoline (essentially, a
>> - * trampoline that has a branch to _mcount()), we re-write the branch to
>> - * instead go to ftrace_[regs_]caller() and note down the location of this
>> - * trampoline.
>> - */
>> -static int setup_mcount_compiler_tramp(unsigned long tramp)
>> -{
>> - int i;
>> - ppc_inst_t op;
>> - unsigned long ptr;
>> -
>> - /* Is this a known long jump tramp? */
>> - for (i = 0; i < NUM_FTRACE_TRAMPS; i++)
>> - if (ftrace_tramps[i] == tramp)
>> - return 0;
>> -
>> - /* New trampoline -- read where this goes */
>> - if (copy_inst_from_kernel_nofault(&op, (void *)tramp)) {
>> - pr_debug("Fetching opcode failed.\n");
>> - return -1;
>> - }
>> -
>> - /* Is this a 24 bit branch? */
>> - if (!is_b_op(op)) {
>> - pr_debug("Trampoline is not a long branch tramp.\n");
>> - return -1;
>> - }
>> -
>> - /* lets find where the pointer goes */
>> - ptr = find_bl_target(tramp, op);
>> -
>> - if (ptr != ppc_global_function_entry((void *)_mcount)) {
>> - pr_debug("Trampoline target %p is not _mcount\n", (void *)ptr);
>> - return -1;
>> - }
>> -
>> - /* Let's re-write the tramp to go to ftrace_[regs_]caller */
>> - if (IS_ENABLED(CONFIG_DYNAMIC_FTRACE_WITH_REGS))
>> - ptr = ppc_global_function_entry((void *)ftrace_regs_caller);
>> - else
>> - ptr = ppc_global_function_entry((void *)ftrace_caller);
>> -
>> - if (patch_branch((u32 *)tramp, ptr, 0)) {
>> - pr_debug("REL24 out of range!\n");
>> - return -1;
>> - }
>> -
>> - if (add_ftrace_tramp(tramp)) {
>> - pr_debug("No tramp locations left\n");
>> - return -1;
>> - }
>> -
>> - return 0;
>> -}
>> -
>> -static int __ftrace_make_nop_kernel(struct dyn_ftrace *rec, unsigned long addr)
>> -{
>> - unsigned long tramp, ip = rec->ip;
>> - ppc_inst_t op;
>> -
>> - /* Read where this goes */
>> - if (copy_inst_from_kernel_nofault(&op, (void *)ip)) {
>> - pr_err("Fetching opcode failed.\n");
>> - return -EFAULT;
>> - }
>> -
>> - /* Make sure that this is still a 24bit jump */
>> - if (!is_bl_op(op)) {
>> - pr_err("Not expected bl: opcode is %08lx\n", ppc_inst_as_ulong(op));
>> - return -EINVAL;
>> - }
>> -
>> - /* Let's find where the pointer goes */
>> - tramp = find_bl_target(ip, op);
>> -
>> - pr_devel("ip:%lx jumps to %lx", ip, tramp);
>> -
>> - if (setup_mcount_compiler_tramp(tramp)) {
>> - /* Are other trampolines reachable? */
>> - if (!find_ftrace_tramp(ip)) {
>> - pr_err("No ftrace trampolines reachable from %ps\n",
>> - (void *)ip);
>> - return -EINVAL;
>> - }
>> - }
>> -
>> - if (patch_instruction((u32 *)ip, ppc_inst(PPC_RAW_NOP()))) {
>> - pr_err("Patching NOP failed.\n");
>> - return -EPERM;
>> - }
>> -
>> - return 0;
>> -}
>> -
>> -int ftrace_make_nop(struct module *mod,
>> - struct dyn_ftrace *rec, unsigned long addr)
>> -{
>> - unsigned long ip = rec->ip;
>> - ppc_inst_t old, new;
>> -
>> - /*
>> - * If the calling address is more that 24 bits away,
>> - * then we had to use a trampoline to make the call.
>> - * Otherwise just update the call site.
>> - */
>> - if (test_24bit_addr(ip, addr)) {
>> - /* within range */
>> - old = ftrace_call_replace(ip, addr, 1);
>> - new = ppc_inst(PPC_RAW_NOP());
>> - return ftrace_modify_code(ip, old, new);
>> - } else if (core_kernel_text(ip)) {
>> - return __ftrace_make_nop_kernel(rec, addr);
>> - } else if (!IS_ENABLED(CONFIG_MODULES)) {
>> - return -EINVAL;
>> - }
>> -
>> - /*
>> - * Out of range jumps are called from modules.
>> - * We should either already have a pointer to the module
>> - * or it has been passed in.
>> - */
>> - if (!rec->arch.mod) {
>> - if (!mod) {
>> - pr_err("No module loaded addr=%lx\n", addr);
>> - return -EFAULT;
>> - }
>> - rec->arch.mod = mod;
>> - } else if (mod) {
>> - if (mod != rec->arch.mod) {
>> - pr_err("Record mod %p not equal to passed in mod %p\n",
>> - rec->arch.mod, mod);
>> - return -EINVAL;
>> - }
>> - /* nothing to do if mod == rec->arch.mod */
>> - } else
>> - mod = rec->arch.mod;
>> -
>> - return __ftrace_make_nop(mod, rec, addr);
>> -}
>> -
>> -#ifdef CONFIG_MODULES
>> -/*
>> - * Examine the existing instructions for __ftrace_make_call.
>> - * They should effectively be a NOP, and follow formal constraints,
>> - * depending on the ABI. Return false if they don't.
>> - */
>> -static bool expected_nop_sequence(void *ip, ppc_inst_t op0, ppc_inst_t op1)
>> -{
>> - if (IS_ENABLED(CONFIG_DYNAMIC_FTRACE_WITH_REGS))
>> - return ppc_inst_equal(op0, ppc_inst(PPC_RAW_NOP()));
>> - else
>> - return ppc_inst_equal(op0, ppc_inst(PPC_RAW_BRANCH(8))) &&
>> - ppc_inst_equal(op1, ppc_inst(PPC_INST_LD_TOC));
>> -}
>> -
>> -static int
>> -__ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr)
>> -{
>> - ppc_inst_t op[2];
>> - void *ip = (void *)rec->ip;
>> - unsigned long entry, ptr, tramp;
>> struct module *mod = rec->arch.mod;
>> -
>> - /* read where this goes */
>> - if (copy_inst_from_kernel_nofault(op, ip))
>> - return -EFAULT;
>> -
>> - if (!IS_ENABLED(CONFIG_DYNAMIC_FTRACE_WITH_REGS) &&
>> - copy_inst_from_kernel_nofault(op + 1, ip + 4))
>> - return -EFAULT;
>> -
>> - if (!expected_nop_sequence(ip, op[0], op[1])) {
>> - pr_err("Unexpected call sequence at %p: %08lx %08lx\n", ip,
>> - ppc_inst_as_ulong(op[0]), ppc_inst_as_ulong(op[1]));
>> - return -EINVAL;
>> - }
>> -
>> - /* If we never set up ftrace trampoline(s), then bail */
>> - if (!mod->arch.tramp ||
>> - (IS_ENABLED(CONFIG_DYNAMIC_FTRACE_WITH_REGS) && !mod->arch.tramp_regs)) {
>> - pr_err("No ftrace trampoline\n");
>> - return -EINVAL;
>> - }
>> -
>> - if (IS_ENABLED(CONFIG_DYNAMIC_FTRACE_WITH_REGS) && rec->flags & FTRACE_FL_REGS)
>> - tramp = mod->arch.tramp_regs;
>> - else
>> - tramp = mod->arch.tramp;
>> -
>> - if (module_trampoline_target(mod, tramp, &ptr)) {
>> - pr_err("Failed to get trampoline target\n");
>> - return -EFAULT;
>> - }
>> -
>> - pr_devel("trampoline target %lx", ptr);
>> -
>> - entry = ppc_global_function_entry((void *)addr);
>> - /* This should match what was called */
>> - if (ptr != entry) {
>> - pr_err("addr %lx does not match expected %lx\n", ptr, entry);
>> - return -EINVAL;
>> - }
>> -
>> - if (patch_branch(ip, tramp, BRANCH_SET_LINK)) {
>> - pr_err("REL24 out of range!\n");
>> - return -EINVAL;
>> - }
>> -
>> - return 0;
>> -}
>> -#else
>> -static int __ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr)
>> -{
>> - return 0;
>> -}
>> -#endif /* CONFIG_MODULES */
>> -
>> -static int __ftrace_make_call_kernel(struct dyn_ftrace *rec, unsigned long addr)
>> -{
>> - ppc_inst_t op;
>> - void *ip = (void *)rec->ip;
>> - unsigned long tramp, entry, ptr;
>> -
>> - /* Make sure we're being asked to patch branch to a known ftrace addr */
>> - entry = ppc_global_function_entry((void *)ftrace_caller);
>> - ptr = ppc_global_function_entry((void *)addr);
>> -
>> - if (ptr != entry && IS_ENABLED(CONFIG_DYNAMIC_FTRACE_WITH_REGS))
>> - entry = ppc_global_function_entry((void *)ftrace_regs_caller);
>> -
>> - if (ptr != entry) {
>> - pr_err("Unknown ftrace addr to patch: %ps\n", (void *)ptr);
>> - return -EINVAL;
>> - }
>> -
>> - /* Make sure we have a nop */
>> - if (copy_inst_from_kernel_nofault(&op, ip)) {
>> - pr_err("Unable to read ftrace location %p\n", ip);
>> - return -EFAULT;
>> - }
>> -
>> - if (!ppc_inst_equal(op, ppc_inst(PPC_RAW_NOP()))) {
>> - pr_err("Unexpected call sequence at %p: %08lx\n",
>> - ip, ppc_inst_as_ulong(op));
>> - return -EINVAL;
>> - }
>> -
>> - tramp = find_ftrace_tramp((unsigned long)ip);
>> - if (!tramp) {
>> - pr_err("No ftrace trampolines reachable from %ps\n", ip);
>> - return -EINVAL;
>> - }
>> -
>> - if (patch_branch(ip, tramp, BRANCH_SET_LINK)) {
>> - pr_err("Error patching branch to ftrace tramp!\n");
>> - return -EINVAL;
>> - }
>> -
>> - return 0;
>> -}
>> -
>> -int ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr)
>> -{
>> unsigned long ip = rec->ip;
>> - ppc_inst_t old, new;
>> + unsigned long stub;
>>
>> - /*
>> - * If the calling address is more that 24 bits away,
>> - * then we had to use a trampoline to make the call.
>> - * Otherwise just update the call site.
>> - */
>> - if (test_24bit_addr(ip, addr)) {
>> - /* within range */
>> - old = ppc_inst(PPC_RAW_NOP());
>> - new = ftrace_call_replace(ip, addr, 1);
>> - return ftrace_modify_code(ip, old, new);
>> + if (is_offset_in_branch_range(addr - ip)) {
>> + /* Within range */
>> + stub = addr;
>> } else if (core_kernel_text(ip)) {
>> - return __ftrace_make_call_kernel(rec, addr);
>> - } else if (!IS_ENABLED(CONFIG_MODULES)) {
>> - /* We should not get here without modules */
>> + /* We would be branching to one of our ftrace stubs */
>> + stub = find_ftrace_tramp(ip);
>> + if (!stub) {
>> + pr_err("0x%lx: No ftrace stubs reachable\n", ip);
>> + return -EINVAL;
>> + }
>> + } else if (IS_ENABLED(CONFIG_MODULES)) {
>> + /* Module code would be going to one of the module stubs */
>> + stub = (addr == (unsigned long)ftrace_caller ? mod->arch.tramp : mod->arch.tramp_regs);
>> + } else {
>> return -EINVAL;
>> }
>>
>> - /*
>> - * Out of range jumps are called from modules.
>> - * Being that we are converting from nop, it had better
>> - * already have a module defined.
>> - */
>> - if (!rec->arch.mod) {
>> - pr_err("No module loaded\n");
>> - return -EINVAL;
>> - }
>> -
>> - return __ftrace_make_call(rec, addr);
>> + *call_inst = ftrace_create_branch_inst(ip, stub, 1);
>> + return 0;
>> }
>>
>> #ifdef CONFIG_DYNAMIC_FTRACE_WITH_REGS
>> -#ifdef CONFIG_MODULES
>> -static int
>> -__ftrace_modify_call(struct dyn_ftrace *rec, unsigned long old_addr,
>> - unsigned long addr)
>> +int ftrace_modify_call(struct dyn_ftrace *rec, unsigned long old_addr, unsigned long addr)
>> {
>> - ppc_inst_t op;
>> - unsigned long ip = rec->ip;
>> - unsigned long entry, ptr, tramp;
>> - struct module *mod = rec->arch.mod;
>> + /* This should never be called since we override ftrace_replace_code() */
>> + WARN_ON(1);
>> + return -EINVAL;
>> +}
>> +#endif
>>
>> - /* If we never set up ftrace trampolines, then bail */
>> - if (!mod->arch.tramp || !mod->arch.tramp_regs) {
>> - pr_err("No ftrace trampoline\n");
>> +int ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr)
>> +{
>> + ppc_inst_t old, new;
>> + int ret;
>> +
>> + /* This can only ever be called during module load */
>> + if (WARN_ON(!IS_ENABLED(CONFIG_MODULES) || core_kernel_text(rec->ip)))
>> + return -EINVAL;
>> +
>> + old = ppc_inst(PPC_RAW_NOP());
>> + ret = ftrace_get_call_inst(rec, addr, &new);
>> + if (ret)
>> + return ret;
>> +
>> + return ftrace_modify_code(rec->ip, old, new);
>> +}
>> +
>> +int ftrace_make_nop(struct module *mod, struct dyn_ftrace *rec, unsigned long addr)
>> +{
>> + /*
>> + * This should never be called since we override ftrace_replace_code(),
>> + * as well as ftrace_init_nop()
>> + */
>> + WARN_ON(1);
>> + return -EINVAL;
>> +}
>> +
>> +void ftrace_replace_code(int enable)
>> +{
>> + ppc_inst_t old, new, nop_inst, call_inst, new_call_inst;
>> + unsigned long ip, new_addr, addr;
>> + struct ftrace_rec_iter *iter;
>> + struct dyn_ftrace *rec;
>> + int ret = 0, update;
>> +
>> + for_ftrace_rec_iter(iter) {
>> + rec = ftrace_rec_iter_record(iter);
>> + update = ftrace_test_record(rec, enable);
>> + ip = rec->ip;
>> + new_addr = 0;
>> +
>> + switch (update) {
>> + case FTRACE_UPDATE_IGNORE:
>> + default:
>> + continue;
>> + case FTRACE_UPDATE_MODIFY_CALL:
>> + addr = ftrace_get_addr_curr(rec);
>> + new_addr = ftrace_get_addr_new(rec);
>> + break;
>> + case FTRACE_UPDATE_MAKE_CALL:
>> + addr = ftrace_get_addr_new(rec);
>> + break;
>> + case FTRACE_UPDATE_MAKE_NOP:
>> + addr = ftrace_get_addr_curr(rec);
>> + break;
>> + }
>> + nop_inst = ppc_inst(PPC_RAW_NOP());
>> + ret = ftrace_get_call_inst(rec, addr, &call_inst);
>> + if (!ret && new_addr)
>> + ret = ftrace_get_call_inst(rec, new_addr, &new_call_inst);
>> + if (ret)
>> + goto out;
>> +
>> + switch (update) {
>> + case FTRACE_UPDATE_MODIFY_CALL:
>> + old = call_inst;
>> + new = new_call_inst;
>> + break;
>> + case FTRACE_UPDATE_MAKE_CALL:
>> + old = nop_inst;
>> + new = call_inst;
>> + break;
>> + case FTRACE_UPDATE_MAKE_NOP:
>> + new = nop_inst;
>> + old = call_inst;
>> + break;
>> + }
>> +
>> + /* old == new when going to .ftrace.text stub for modify */
>> + if (!ppc_inst_equal(old, new))
>> + ret = ftrace_modify_code(ip, old, new);
>> + if (ret)
>> + goto out;
>> + ftrace_update_record(rec, enable);
>> + }
>> +
>> +out:
>> + if (ret)
>> + ftrace_bug(ret, rec);
>> + return;
>> +}
>> +
>> +int ftrace_init_nop(struct module *mod, struct dyn_ftrace *rec)
>> +{
>> + unsigned long addr, ip = rec->ip;
>> + ppc_inst_t old, new;
>> + int ret = 0;
>> +
>> + /* Verify instructions surrounding the ftrace location */
>> + if (IS_ENABLED(CONFIG_ARCH_USING_PATCHABLE_FUNCTION_ENTRY)) {
>> + /* Expect nops */
>> + ret = ftrace_validate_inst(ip - 4, ppc_inst(PPC_RAW_NOP()));
>> + if (!ret)
>> + ret = ftrace_validate_inst(ip, ppc_inst(PPC_RAW_NOP()));
>> + } else if (IS_ENABLED(CONFIG_PPC32)) {
>> + /* Expected sequence: 'mflr r0', 'stw r0,4(r1)', 'bl _mcount' */
>> + ret = ftrace_validate_inst(ip - 8, ppc_inst(PPC_RAW_MFLR(_R0)));
>> + if (!ret)
>> + ret = ftrace_validate_inst(ip - 4, ppc_inst(PPC_RAW_STW(_R0, _R1, 4)));
>> + } else if (IS_ENABLED(CONFIG_MPROFILE_KERNEL)) {
>> + /* Expected sequence: 'mflr r0', 'bl _mcount' */
>> + ret = ftrace_validate_inst(ip - 4, ppc_inst(PPC_RAW_MFLR(_R0)));
>> + } else {
>> return -EINVAL;
>> }
>>
>> - /* read where this goes */
>> - if (copy_inst_from_kernel_nofault(&op, (void *)ip)) {
>> - pr_err("Fetching opcode failed.\n");
>> - return -EFAULT;
>> - }
>> + if (ret)
>> + return ret;
>>
>> - /* Make sure that this is still a 24bit jump */
>> - if (!is_bl_op(op)) {
>> - pr_err("Not expected bl: opcode is %08lx\n", ppc_inst_as_ulong(op));
>> - return -EINVAL;
>> - }
>> -
>> - /* lets find where the pointer goes */
>> - tramp = find_bl_target(ip, op);
>> - entry = ppc_global_function_entry((void *)old_addr);
>> -
>> - pr_devel("ip:%lx jumps to %lx", ip, tramp);
>> -
>> - if (tramp != entry) {
>> - /* old_addr is not within range, so we must have used a trampoline */
>> - if (module_trampoline_target(mod, tramp, &ptr)) {
>> - pr_err("Failed to get trampoline target\n");
>> + if (!core_kernel_text(ip)) {
>> + if (!mod) {
>> + pr_err("0x%lx: No module provided for non-kernel address\n", ip);
>> return -EFAULT;
>> }
>> -
>> - pr_devel("trampoline target %lx", ptr);
>> -
>> - /* This should match what was called */
>> - if (ptr != entry) {
>> - pr_err("addr %lx does not match expected %lx\n", ptr, entry);
>> - return -EINVAL;
>> - }
>> + rec->arch.mod = mod;
>> }
>>
>> - /* The new target may be within range */
>> - if (test_24bit_addr(ip, addr)) {
>> - /* within range */
>> - if (patch_branch((u32 *)ip, addr, BRANCH_SET_LINK)) {
>> - pr_err("REL24 out of range!\n");
>> - return -EINVAL;
>> - }
>> -
>> - return 0;
>> - }
>> -
>> - if (rec->flags & FTRACE_FL_REGS)
>> - tramp = mod->arch.tramp_regs;
>> - else
>> - tramp = mod->arch.tramp;
>> -
>> - if (module_trampoline_target(mod, tramp, &ptr)) {
>> - pr_err("Failed to get trampoline target\n");
>> - return -EFAULT;
>> - }
>> -
>> - pr_devel("trampoline target %lx", ptr);
>> -
>> - entry = ppc_global_function_entry((void *)addr);
>> - /* This should match what was called */
>> - if (ptr != entry) {
>> - pr_err("addr %lx does not match expected %lx\n", ptr, entry);
>> - return -EINVAL;
>> - }
>> -
>> - if (patch_branch((u32 *)ip, tramp, BRANCH_SET_LINK)) {
>> - pr_err("REL24 out of range!\n");
>> - return -EINVAL;
>> - }
>> -
>> - return 0;
>> -}
>> -#else
>> -static int __ftrace_modify_call(struct dyn_ftrace *rec, unsigned long old_addr, unsigned long addr)
>> -{
>> - return 0;
>> -}
>> -#endif
>> -
>> -int ftrace_modify_call(struct dyn_ftrace *rec, unsigned long old_addr,
>> - unsigned long addr)
>> -{
>> - unsigned long ip = rec->ip;
>> - ppc_inst_t old, new;
>> -
>> - /*
>> - * If the calling address is more that 24 bits away,
>> - * then we had to use a trampoline to make the call.
>> - * Otherwise just update the call site.
>> - */
>> - if (test_24bit_addr(ip, addr) && test_24bit_addr(ip, old_addr)) {
>> - /* within range */
>> - old = ftrace_call_replace(ip, old_addr, 1);
>> - new = ftrace_call_replace(ip, addr, 1);
>> - return ftrace_modify_code(ip, old, new);
>> - } else if (core_kernel_text(ip)) {
>> + /* Nop-out the ftrace location */
>> + new = ppc_inst(PPC_RAW_NOP());
>> + addr = MCOUNT_ADDR;
>> + if (IS_ENABLED(CONFIG_ARCH_USING_PATCHABLE_FUNCTION_ENTRY)) {
>> + /* we instead patch-in the 'mflr r0' */
>> + old = ppc_inst(PPC_RAW_NOP());
>> + new = ppc_inst(PPC_RAW_MFLR(_R0));
>> + ret = ftrace_modify_code(ip - 4, old, new);
>> + } else if (is_offset_in_branch_range(addr - ip)) {
>> + /* Within range */
>> + old = ftrace_create_branch_inst(ip, addr, 1);
>> + ret = ftrace_modify_code(ip, old, new);
>> + } else if (core_kernel_text(ip) || (IS_ENABLED(CONFIG_MODULES) && mod)) {
>> /*
>> - * We always patch out of range locations to go to the regs
>> - * variant, so there is nothing to do here
>> + * We would be branching to a toolchain-generated stub, or to the module _mcount
>> + * stub. Let's just confirm we have a 'bl' here.
>> */
>> - return 0;
>> - } else if (!IS_ENABLED(CONFIG_MODULES)) {
>> - /* We should not get here without modules */
>> + ret = ftrace_read_inst(ip, &old);
>> + if (ret)
>> + return ret;
>> + if (!is_bl_op(old)) {
>> + pr_err("0x%lx: expected (bl) != found (%08lx)\n", ip, ppc_inst_as_ulong(old));
>> + return -EINVAL;
>> + }
>> + ret = patch_instruction((u32 *)ip, new);
>> + } else {
>> return -EINVAL;
>> }
>>
>> - /*
>> - * Out of range jumps are called from modules.
>> - */
>> - if (!rec->arch.mod) {
>> - pr_err("No module loaded\n");
>> - return -EINVAL;
>> - }
>> -
>> - return __ftrace_modify_call(rec, old_addr, addr);
>> + return ret;
>> }
>> -#endif
>>
>> int ftrace_update_ftrace_func(ftrace_func_t func)
>> {
>> @@ -684,14 +296,14 @@ int ftrace_update_ftrace_func(ftrace_func_t func)
>> int ret;
>>
>> old = ppc_inst_read((u32 *)&ftrace_call);
>> - new = ftrace_call_replace(ip, (unsigned long)func, 1);
>> + new = ftrace_create_branch_inst(ip, ppc_function_entry(func), 1);
>> ret = ftrace_modify_code(ip, old, new);
>>
>> /* Also update the regs callback function */
>> if (IS_ENABLED(CONFIG_DYNAMIC_FTRACE_WITH_REGS) && !ret) {
>> ip = (unsigned long)(&ftrace_regs_call);
>> old = ppc_inst_read((u32 *)&ftrace_regs_call);
>> - new = ftrace_call_replace(ip, (unsigned long)func, 1);
>> + new = ftrace_create_branch_inst(ip, ppc_function_entry(func), 1);
>> ret = ftrace_modify_code(ip, old, new);
>> }
>>
>> @@ -723,6 +335,17 @@ void ftrace_free_init_tramp(void)
>> }
>> }
>>
>> +static void __init add_ftrace_tramp(unsigned long tramp)
>> +{
>> + int i;
>> +
>> + for (i = 0; i < NUM_FTRACE_TRAMPS; i++)
>> + if (!ftrace_tramps[i]) {
>> + ftrace_tramps[i] = tramp;
>> + return;
>> + }
>> +}
>> +
>> int __init ftrace_dyn_arch_init(void)
>> {
>> int i;
>> @@ -745,14 +368,9 @@ int __init ftrace_dyn_arch_init(void)
>> };
>> #endif
>>
>> - unsigned long addr;
>> + unsigned long addr = FTRACE_REGS_ADDR;
>> long reladdr;
>>
>> - if (IS_ENABLED(CONFIG_DYNAMIC_FTRACE_WITH_REGS))
>> - addr = ppc_global_function_entry((void *)ftrace_regs_caller);
>> - else
>> - addr = ppc_global_function_entry((void *)ftrace_caller);
>> -
>> if (IS_ENABLED(CONFIG_PPC_KERNEL_PCREL)) {
>> for (i = 0; i < 2; i++) {
>> reladdr = addr - (unsigned long)tramp[i];
>> @@ -804,8 +422,8 @@ static int ftrace_modify_ftrace_graph_caller(bool enable)
>> if (IS_ENABLED(CONFIG_DYNAMIC_FTRACE_WITH_ARGS))
>> return 0;
>>
>> - old = ftrace_call_replace(ip, enable ? stub : addr, 0);
>> - new = ftrace_call_replace(ip, enable ? addr : stub, 0);
>> + old = ftrace_create_branch_inst(ip, enable ? stub : addr, 0);
>> + new = ftrace_create_branch_inst(ip, enable ? addr : stub, 0);
>>
>> return ftrace_modify_code(ip, old, new);
>> }
>> @@ -864,13 +482,3 @@ unsigned long prepare_ftrace_return(unsigned long parent, unsigned long ip,
>> }
>> #endif
>> #endif /* CONFIG_FUNCTION_GRAPH_TRACER */
>> -
>> -#ifdef CONFIG_PPC64_ELF_ABI_V1
>> -char *arch_ftrace_match_adjust(char *str, const char *search)
>> -{
>> - if (str[0] == '.' && search[0] != '.')
>> - return str + 1;
>> - else
>> - return str;
>> -}
>> -#endif /* CONFIG_PPC64_ELF_ABI_V1 */
>> diff --git a/arch/powerpc/kernel/trace/ftrace_pg.c b/arch/powerpc/kernel/trace/ftrace_pg.c
>> new file mode 100644
>> index 00000000000000..7b85c3b460a3c0
>> --- /dev/null
>> +++ b/arch/powerpc/kernel/trace/ftrace_pg.c
>> @@ -0,0 +1,846 @@
>> +// SPDX-License-Identifier: GPL-2.0
>> +/*
>> + * Code for replacing ftrace calls with jumps.
>> + *
>> + * Copyright (C) 2007-2008 Steven Rostedt <srostedt at redhat.com>
>> + *
>> + * Thanks goes out to P.A. Semi, Inc for supplying me with a PPC64 box.
>> + *
>> + * Added function graph tracer code, taken from x86 that was written
>> + * by Frederic Weisbecker, and ported to PPC by Steven Rostedt.
>> + *
>> + */
>> +
>> +#define pr_fmt(fmt) "ftrace-powerpc: " fmt
>> +
>> +#include <linux/spinlock.h>
>> +#include <linux/hardirq.h>
>> +#include <linux/uaccess.h>
>> +#include <linux/module.h>
>> +#include <linux/ftrace.h>
>> +#include <linux/percpu.h>
>> +#include <linux/init.h>
>> +#include <linux/list.h>
>> +
>> +#include <asm/cacheflush.h>
>> +#include <asm/code-patching.h>
>> +#include <asm/ftrace.h>
>> +#include <asm/syscall.h>
>> +#include <asm/inst.h>
>> +
>> +/*
>> + * We generally only have a single long_branch tramp and at most 2 or 3 plt
>> + * tramps generated. But, we don't use the plt tramps currently. We also allot
>> + * 2 tramps after .text and .init.text. So, we only end up with around 3 usable
>> + * tramps in total. Set aside 8 just to be sure.
>> + */
>> +#define NUM_FTRACE_TRAMPS 8
>> +static unsigned long ftrace_tramps[NUM_FTRACE_TRAMPS];
>> +
>> +static ppc_inst_t
>> +ftrace_call_replace(unsigned long ip, unsigned long addr, int link)
>> +{
>> + ppc_inst_t op;
>> +
>> + addr = ppc_function_entry((void *)addr);
>> +
>> + /* if (link) set op to 'bl' else 'b' */
>> + create_branch(&op, (u32 *)ip, addr, link ? BRANCH_SET_LINK : 0);
>> +
>> + return op;
>> +}
>> +
>> +static inline int
>> +ftrace_modify_code(unsigned long ip, ppc_inst_t old, ppc_inst_t new)
>> +{
>> + ppc_inst_t replaced;
>> +
>> + /*
>> + * Note:
>> + * We are paranoid about modifying text, as if a bug was to happen, it
>> + * could cause us to read or write to someplace that could cause harm.
>> + * Carefully read and modify the code with probe_kernel_*(), and make
>> + * sure what we read is what we expected it to be before modifying it.
>> + */
>> +
>> + /* read the text we want to modify */
>> + if (copy_inst_from_kernel_nofault(&replaced, (void *)ip))
>> + return -EFAULT;
>> +
>> + /* Make sure it is what we expect it to be */
>> + if (!ppc_inst_equal(replaced, old)) {
>> + pr_err("%p: replaced (%08lx) != old (%08lx)", (void *)ip,
>> + ppc_inst_as_ulong(replaced), ppc_inst_as_ulong(old));
>> + return -EINVAL;
>> + }
>> +
>> + /* replace the text with the new text */
>> + return patch_instruction((u32 *)ip, new);
>> +}
>> +
>> +/*
>> + * Helper functions that are the same for both PPC64 and PPC32.
>> + */
>> +static int test_24bit_addr(unsigned long ip, unsigned long addr)
>> +{
>> + addr = ppc_function_entry((void *)addr);
>> +
>> + return is_offset_in_branch_range(addr - ip);
>> +}
>> +
>> +static int is_bl_op(ppc_inst_t op)
>> +{
>> + return (ppc_inst_val(op) & ~PPC_LI_MASK) == PPC_RAW_BL(0);
>> +}
>> +
>> +static int is_b_op(ppc_inst_t op)
>> +{
>> + return (ppc_inst_val(op) & ~PPC_LI_MASK) == PPC_RAW_BRANCH(0);
>> +}
>> +
>> +static unsigned long find_bl_target(unsigned long ip, ppc_inst_t op)
>> +{
>> + int offset;
>> +
>> + offset = PPC_LI(ppc_inst_val(op));
>> + /* make it signed */
>> + if (offset & 0x02000000)
>> + offset |= 0xfe000000;
>> +
>> + return ip + (long)offset;
>> +}
>> +
>> +#ifdef CONFIG_MODULES
>> +static int
>> +__ftrace_make_nop(struct module *mod,
>> + struct dyn_ftrace *rec, unsigned long addr)
>> +{
>> + unsigned long entry, ptr, tramp;
>> + unsigned long ip = rec->ip;
>> + ppc_inst_t op, pop;
>> +
>> + /* read where this goes */
>> + if (copy_inst_from_kernel_nofault(&op, (void *)ip)) {
>> + pr_err("Fetching opcode failed.\n");
>> + return -EFAULT;
>> + }
>> +
>> + /* Make sure that this is still a 24bit jump */
>> + if (!is_bl_op(op)) {
>> + pr_err("Not expected bl: opcode is %08lx\n", ppc_inst_as_ulong(op));
>> + return -EINVAL;
>> + }
>> +
>> + /* lets find where the pointer goes */
>> + tramp = find_bl_target(ip, op);
>> +
>> + pr_devel("ip:%lx jumps to %lx", ip, tramp);
>> +
>> + if (module_trampoline_target(mod, tramp, &ptr)) {
>> + pr_err("Failed to get trampoline target\n");
>> + return -EFAULT;
>> + }
>> +
>> + pr_devel("trampoline target %lx", ptr);
>> +
>> + entry = ppc_global_function_entry((void *)addr);
>> + /* This should match what was called */
>> + if (ptr != entry) {
>> + pr_err("addr %lx does not match expected %lx\n", ptr, entry);
>> + return -EINVAL;
>> + }
>> +
>> + if (IS_ENABLED(CONFIG_MPROFILE_KERNEL)) {
>> + if (copy_inst_from_kernel_nofault(&op, (void *)(ip - 4))) {
>> + pr_err("Fetching instruction at %lx failed.\n", ip - 4);
>> + return -EFAULT;
>> + }
>> +
>> + /* We expect either a mflr r0, or a std r0, LRSAVE(r1) */
>> + if (!ppc_inst_equal(op, ppc_inst(PPC_RAW_MFLR(_R0))) &&
>> + !ppc_inst_equal(op, ppc_inst(PPC_INST_STD_LR))) {
>> + pr_err("Unexpected instruction %08lx around bl _mcount\n",
>> + ppc_inst_as_ulong(op));
>> + return -EINVAL;
>> + }
>> + } else if (IS_ENABLED(CONFIG_PPC64)) {
>> + /*
>> + * Check what is in the next instruction. We can see ld r2,40(r1), but
>> + * on first pass after boot we will see mflr r0.
>> + */
>> + if (copy_inst_from_kernel_nofault(&op, (void *)(ip + 4))) {
>> + pr_err("Fetching op failed.\n");
>> + return -EFAULT;
>> + }
>> +
>> + if (!ppc_inst_equal(op, ppc_inst(PPC_INST_LD_TOC))) {
>> + pr_err("Expected %08lx found %08lx\n", PPC_INST_LD_TOC,
>> + ppc_inst_as_ulong(op));
>> + return -EINVAL;
>> + }
>> + }
>> +
>> + /*
>> + * When using -mprofile-kernel or PPC32 there is no load to jump over.
>> + *
>> + * Otherwise our original call site looks like:
>> + *
>> + * bl <tramp>
>> + * ld r2,XX(r1)
>> + *
>> + * Milton Miller pointed out that we can not simply nop the branch.
>> + * If a task was preempted when calling a trace function, the nops
>> + * will remove the way to restore the TOC in r2 and the r2 TOC will
>> + * get corrupted.
>> + *
>> + * Use a b +8 to jump over the load.
>> + */
>> + if (IS_ENABLED(CONFIG_MPROFILE_KERNEL) || IS_ENABLED(CONFIG_PPC32))
>> + pop = ppc_inst(PPC_RAW_NOP());
>> + else
>> + pop = ppc_inst(PPC_RAW_BRANCH(8)); /* b +8 */
>> +
>> + if (patch_instruction((u32 *)ip, pop)) {
>> + pr_err("Patching NOP failed.\n");
>> + return -EPERM;
>> + }
>> +
>> + return 0;
>> +}
>> +#else
>> +static int __ftrace_make_nop(struct module *mod, struct dyn_ftrace *rec, unsigned long addr)
>> +{
>> + return 0;
>> +}
>> +#endif /* CONFIG_MODULES */
>> +
>> +static unsigned long find_ftrace_tramp(unsigned long ip)
>> +{
>> + int i;
>> +
>> + /*
>> + * We have the compiler generated long_branch tramps at the end
>> + * and we prefer those
>> + */
>> + for (i = NUM_FTRACE_TRAMPS - 1; i >= 0; i--)
>> + if (!ftrace_tramps[i])
>> + continue;
>> + else if (is_offset_in_branch_range(ftrace_tramps[i] - ip))
>> + return ftrace_tramps[i];
>> +
>> + return 0;
>> +}
>> +
>> +static int add_ftrace_tramp(unsigned long tramp)
>> +{
>> + int i;
>> +
>> + for (i = 0; i < NUM_FTRACE_TRAMPS; i++)
>> + if (!ftrace_tramps[i]) {
>> + ftrace_tramps[i] = tramp;
>> + return 0;
>> + }
>> +
>> + return -1;
>> +}
>> +
>> +/*
>> + * If this is a compiler generated long_branch trampoline (essentially, a
>> + * trampoline that has a branch to _mcount()), we re-write the branch to
>> + * instead go to ftrace_[regs_]caller() and note down the location of this
>> + * trampoline.
>> + */
>> +static int setup_mcount_compiler_tramp(unsigned long tramp)
>> +{
>> + int i;
>> + ppc_inst_t op;
>> + unsigned long ptr;
>> +
>> + /* Is this a known long jump tramp? */
>> + for (i = 0; i < NUM_FTRACE_TRAMPS; i++)
>> + if (ftrace_tramps[i] == tramp)
>> + return 0;
>> +
>> + /* New trampoline -- read where this goes */
>> + if (copy_inst_from_kernel_nofault(&op, (void *)tramp)) {
>> + pr_debug("Fetching opcode failed.\n");
>> + return -1;
>> + }
>> +
>> + /* Is this a 24 bit branch? */
>> + if (!is_b_op(op)) {
>> + pr_debug("Trampoline is not a long branch tramp.\n");
>> + return -1;
>> + }
>> +
>> + /* lets find where the pointer goes */
>> + ptr = find_bl_target(tramp, op);
>> +
>> + if (ptr != ppc_global_function_entry((void *)_mcount)) {
>> + pr_debug("Trampoline target %p is not _mcount\n", (void *)ptr);
>> + return -1;
>> + }
>> +
>> + /* Let's re-write the tramp to go to ftrace_[regs_]caller */
>> + if (IS_ENABLED(CONFIG_DYNAMIC_FTRACE_WITH_REGS))
>> + ptr = ppc_global_function_entry((void *)ftrace_regs_caller);
>> + else
>> + ptr = ppc_global_function_entry((void *)ftrace_caller);
>> +
>> + if (patch_branch((u32 *)tramp, ptr, 0)) {
>> + pr_debug("REL24 out of range!\n");
>> + return -1;
>> + }
>> +
>> + if (add_ftrace_tramp(tramp)) {
>> + pr_debug("No tramp locations left\n");
>> + return -1;
>> + }
>> +
>> + return 0;
>> +}
>> +
>> +static int __ftrace_make_nop_kernel(struct dyn_ftrace *rec, unsigned long addr)
>> +{
>> + unsigned long tramp, ip = rec->ip;
>> + ppc_inst_t op;
>> +
>> + /* Read where this goes */
>> + if (copy_inst_from_kernel_nofault(&op, (void *)ip)) {
>> + pr_err("Fetching opcode failed.\n");
>> + return -EFAULT;
>> + }
>> +
>> + /* Make sure that this is still a 24bit jump */
>> + if (!is_bl_op(op)) {
>> + pr_err("Not expected bl: opcode is %08lx\n", ppc_inst_as_ulong(op));
>> + return -EINVAL;
>> + }
>> +
>> + /* Let's find where the pointer goes */
>> + tramp = find_bl_target(ip, op);
>> +
>> + pr_devel("ip:%lx jumps to %lx", ip, tramp);
>> +
>> + if (setup_mcount_compiler_tramp(tramp)) {
>> + /* Are other trampolines reachable? */
>> + if (!find_ftrace_tramp(ip)) {
>> + pr_err("No ftrace trampolines reachable from %ps\n",
>> + (void *)ip);
>> + return -EINVAL;
>> + }
>> + }
>> +
>> + if (patch_instruction((u32 *)ip, ppc_inst(PPC_RAW_NOP()))) {
>> + pr_err("Patching NOP failed.\n");
>> + return -EPERM;
>> + }
>> +
>> + return 0;
>> +}
>> +
>> +int ftrace_make_nop(struct module *mod,
>> + struct dyn_ftrace *rec, unsigned long addr)
>> +{
>> + unsigned long ip = rec->ip;
>> + ppc_inst_t old, new;
>> +
>> + /*
>> + * If the calling address is more that 24 bits away,
>> + * then we had to use a trampoline to make the call.
>> + * Otherwise just update the call site.
>> + */
>> + if (test_24bit_addr(ip, addr)) {
>> + /* within range */
>> + old = ftrace_call_replace(ip, addr, 1);
>> + new = ppc_inst(PPC_RAW_NOP());
>> + return ftrace_modify_code(ip, old, new);
>> + } else if (core_kernel_text(ip)) {
>> + return __ftrace_make_nop_kernel(rec, addr);
>> + } else if (!IS_ENABLED(CONFIG_MODULES)) {
>> + return -EINVAL;
>> + }
>> +
>> + /*
>> + * Out of range jumps are called from modules.
>> + * We should either already have a pointer to the module
>> + * or it has been passed in.
>> + */
>> + if (!rec->arch.mod) {
>> + if (!mod) {
>> + pr_err("No module loaded addr=%lx\n", addr);
>> + return -EFAULT;
>> + }
>> + rec->arch.mod = mod;
>> + } else if (mod) {
>> + if (mod != rec->arch.mod) {
>> + pr_err("Record mod %p not equal to passed in mod %p\n",
>> + rec->arch.mod, mod);
>> + return -EINVAL;
>> + }
>> + /* nothing to do if mod == rec->arch.mod */
>> + } else
>> + mod = rec->arch.mod;
>> +
>> + return __ftrace_make_nop(mod, rec, addr);
>> +}
>> +
>> +#ifdef CONFIG_MODULES
>> +/*
>> + * Examine the existing instructions for __ftrace_make_call.
>> + * They should effectively be a NOP, and follow formal constraints,
>> + * depending on the ABI. Return false if they don't.
>> + */
>> +static bool expected_nop_sequence(void *ip, ppc_inst_t op0, ppc_inst_t op1)
>> +{
>> + if (IS_ENABLED(CONFIG_DYNAMIC_FTRACE_WITH_REGS))
>> + return ppc_inst_equal(op0, ppc_inst(PPC_RAW_NOP()));
>> + else
>> + return ppc_inst_equal(op0, ppc_inst(PPC_RAW_BRANCH(8))) &&
>> + ppc_inst_equal(op1, ppc_inst(PPC_INST_LD_TOC));
>> +}
>> +
>> +static int
>> +__ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr)
>> +{
>> + ppc_inst_t op[2];
>> + void *ip = (void *)rec->ip;
>> + unsigned long entry, ptr, tramp;
>> + struct module *mod = rec->arch.mod;
>> +
>> + /* read where this goes */
>> + if (copy_inst_from_kernel_nofault(op, ip))
>> + return -EFAULT;
>> +
>> + if (!IS_ENABLED(CONFIG_DYNAMIC_FTRACE_WITH_REGS) &&
>> + copy_inst_from_kernel_nofault(op + 1, ip + 4))
>> + return -EFAULT;
>> +
>> + if (!expected_nop_sequence(ip, op[0], op[1])) {
>> + pr_err("Unexpected call sequence at %p: %08lx %08lx\n", ip,
>> + ppc_inst_as_ulong(op[0]), ppc_inst_as_ulong(op[1]));
>> + return -EINVAL;
>> + }
>> +
>> + /* If we never set up ftrace trampoline(s), then bail */
>> + if (!mod->arch.tramp ||
>> + (IS_ENABLED(CONFIG_DYNAMIC_FTRACE_WITH_REGS) && !mod->arch.tramp_regs)) {
>> + pr_err("No ftrace trampoline\n");
>> + return -EINVAL;
>> + }
>> +
>> + if (IS_ENABLED(CONFIG_DYNAMIC_FTRACE_WITH_REGS) && rec->flags & FTRACE_FL_REGS)
>> + tramp = mod->arch.tramp_regs;
>> + else
>> + tramp = mod->arch.tramp;
>> +
>> + if (module_trampoline_target(mod, tramp, &ptr)) {
>> + pr_err("Failed to get trampoline target\n");
>> + return -EFAULT;
>> + }
>> +
>> + pr_devel("trampoline target %lx", ptr);
>> +
>> + entry = ppc_global_function_entry((void *)addr);
>> + /* This should match what was called */
>> + if (ptr != entry) {
>> + pr_err("addr %lx does not match expected %lx\n", ptr, entry);
>> + return -EINVAL;
>> + }
>> +
>> + if (patch_branch(ip, tramp, BRANCH_SET_LINK)) {
>> + pr_err("REL24 out of range!\n");
>> + return -EINVAL;
>> + }
>> +
>> + return 0;
>> +}
>> +#else
>> +static int __ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr)
>> +{
>> + return 0;
>> +}
>> +#endif /* CONFIG_MODULES */
>> +
>> +static int __ftrace_make_call_kernel(struct dyn_ftrace *rec, unsigned long addr)
>> +{
>> + ppc_inst_t op;
>> + void *ip = (void *)rec->ip;
>> + unsigned long tramp, entry, ptr;
>> +
>> + /* Make sure we're being asked to patch branch to a known ftrace addr */
>> + entry = ppc_global_function_entry((void *)ftrace_caller);
>> + ptr = ppc_global_function_entry((void *)addr);
>> +
>> + if (ptr != entry && IS_ENABLED(CONFIG_DYNAMIC_FTRACE_WITH_REGS))
>> + entry = ppc_global_function_entry((void *)ftrace_regs_caller);
>> +
>> + if (ptr != entry) {
>> + pr_err("Unknown ftrace addr to patch: %ps\n", (void *)ptr);
>> + return -EINVAL;
>> + }
>> +
>> + /* Make sure we have a nop */
>> + if (copy_inst_from_kernel_nofault(&op, ip)) {
>> + pr_err("Unable to read ftrace location %p\n", ip);
>> + return -EFAULT;
>> + }
>> +
>> + if (!ppc_inst_equal(op, ppc_inst(PPC_RAW_NOP()))) {
>> + pr_err("Unexpected call sequence at %p: %08lx\n",
>> + ip, ppc_inst_as_ulong(op));
>> + return -EINVAL;
>> + }
>> +
>> + tramp = find_ftrace_tramp((unsigned long)ip);
>> + if (!tramp) {
>> + pr_err("No ftrace trampolines reachable from %ps\n", ip);
>> + return -EINVAL;
>> + }
>> +
>> + if (patch_branch(ip, tramp, BRANCH_SET_LINK)) {
>> + pr_err("Error patching branch to ftrace tramp!\n");
>> + return -EINVAL;
>> + }
>> +
>> + return 0;
>> +}
>> +
>> +int ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr)
>> +{
>> + unsigned long ip = rec->ip;
>> + ppc_inst_t old, new;
>> +
>> + /*
>> + * If the calling address is more that 24 bits away,
>> + * then we had to use a trampoline to make the call.
>> + * Otherwise just update the call site.
>> + */
>> + if (test_24bit_addr(ip, addr)) {
>> + /* within range */
>> + old = ppc_inst(PPC_RAW_NOP());
>> + new = ftrace_call_replace(ip, addr, 1);
>> + return ftrace_modify_code(ip, old, new);
>> + } else if (core_kernel_text(ip)) {
>> + return __ftrace_make_call_kernel(rec, addr);
>> + } else if (!IS_ENABLED(CONFIG_MODULES)) {
>> + /* We should not get here without modules */
>> + return -EINVAL;
>> + }
>> +
>> + /*
>> + * Out of range jumps are called from modules.
>> + * Being that we are converting from nop, it had better
>> + * already have a module defined.
>> + */
>> + if (!rec->arch.mod) {
>> + pr_err("No module loaded\n");
>> + return -EINVAL;
>> + }
>> +
>> + return __ftrace_make_call(rec, addr);
>> +}
>> +
>> +#ifdef CONFIG_DYNAMIC_FTRACE_WITH_REGS
>> +#ifdef CONFIG_MODULES
>> +static int
>> +__ftrace_modify_call(struct dyn_ftrace *rec, unsigned long old_addr,
>> + unsigned long addr)
>> +{
>> + ppc_inst_t op;
>> + unsigned long ip = rec->ip;
>> + unsigned long entry, ptr, tramp;
>> + struct module *mod = rec->arch.mod;
>> +
>> + /* If we never set up ftrace trampolines, then bail */
>> + if (!mod->arch.tramp || !mod->arch.tramp_regs) {
>> + pr_err("No ftrace trampoline\n");
>> + return -EINVAL;
>> + }
>> +
>> + /* read where this goes */
>> + if (copy_inst_from_kernel_nofault(&op, (void *)ip)) {
>> + pr_err("Fetching opcode failed.\n");
>> + return -EFAULT;
>> + }
>> +
>> + /* Make sure that this is still a 24bit jump */
>> + if (!is_bl_op(op)) {
>> + pr_err("Not expected bl: opcode is %08lx\n", ppc_inst_as_ulong(op));
>> + return -EINVAL;
>> + }
>> +
>> + /* lets find where the pointer goes */
>> + tramp = find_bl_target(ip, op);
>> + entry = ppc_global_function_entry((void *)old_addr);
>> +
>> + pr_devel("ip:%lx jumps to %lx", ip, tramp);
>> +
>> + if (tramp != entry) {
>> + /* old_addr is not within range, so we must have used a trampoline */
>> + if (module_trampoline_target(mod, tramp, &ptr)) {
>> + pr_err("Failed to get trampoline target\n");
>> + return -EFAULT;
>> + }
>> +
>> + pr_devel("trampoline target %lx", ptr);
>> +
>> + /* This should match what was called */
>> + if (ptr != entry) {
>> + pr_err("addr %lx does not match expected %lx\n", ptr, entry);
>> + return -EINVAL;
>> + }
>> + }
>> +
>> + /* The new target may be within range */
>> + if (test_24bit_addr(ip, addr)) {
>> + /* within range */
>> + if (patch_branch((u32 *)ip, addr, BRANCH_SET_LINK)) {
>> + pr_err("REL24 out of range!\n");
>> + return -EINVAL;
>> + }
>> +
>> + return 0;
>> + }
>> +
>> + if (rec->flags & FTRACE_FL_REGS)
>> + tramp = mod->arch.tramp_regs;
>> + else
>> + tramp = mod->arch.tramp;
>> +
>> + if (module_trampoline_target(mod, tramp, &ptr)) {
>> + pr_err("Failed to get trampoline target\n");
>> + return -EFAULT;
>> + }
>> +
>> + pr_devel("trampoline target %lx", ptr);
>> +
>> + entry = ppc_global_function_entry((void *)addr);
>> + /* This should match what was called */
>> + if (ptr != entry) {
>> + pr_err("addr %lx does not match expected %lx\n", ptr, entry);
>> + return -EINVAL;
>> + }
>> +
>> + if (patch_branch((u32 *)ip, tramp, BRANCH_SET_LINK)) {
>> + pr_err("REL24 out of range!\n");
>> + return -EINVAL;
>> + }
>> +
>> + return 0;
>> +}
>> +#else
>> +static int __ftrace_modify_call(struct dyn_ftrace *rec, unsigned long old_addr, unsigned long addr)
>> +{
>> + return 0;
>> +}
>> +#endif
>> +
>> +int ftrace_modify_call(struct dyn_ftrace *rec, unsigned long old_addr,
>> + unsigned long addr)
>> +{
>> + unsigned long ip = rec->ip;
>> + ppc_inst_t old, new;
>> +
>> + /*
>> + * If the calling address is more that 24 bits away,
>> + * then we had to use a trampoline to make the call.
>> + * Otherwise just update the call site.
>> + */
>> + if (test_24bit_addr(ip, addr) && test_24bit_addr(ip, old_addr)) {
>> + /* within range */
>> + old = ftrace_call_replace(ip, old_addr, 1);
>> + new = ftrace_call_replace(ip, addr, 1);
>> + return ftrace_modify_code(ip, old, new);
>> + } else if (core_kernel_text(ip)) {
>> + /*
>> + * We always patch out of range locations to go to the regs
>> + * variant, so there is nothing to do here
>> + */
>> + return 0;
>> + } else if (!IS_ENABLED(CONFIG_MODULES)) {
>> + /* We should not get here without modules */
>> + return -EINVAL;
>> + }
>> +
>> + /*
>> + * Out of range jumps are called from modules.
>> + */
>> + if (!rec->arch.mod) {
>> + pr_err("No module loaded\n");
>> + return -EINVAL;
>> + }
>> +
>> + return __ftrace_modify_call(rec, old_addr, addr);
>> +}
>> +#endif
>> +
>> +int ftrace_update_ftrace_func(ftrace_func_t func)
>> +{
>> + unsigned long ip = (unsigned long)(&ftrace_call);
>> + ppc_inst_t old, new;
>> + int ret;
>> +
>> + old = ppc_inst_read((u32 *)&ftrace_call);
>> + new = ftrace_call_replace(ip, (unsigned long)func, 1);
>> + ret = ftrace_modify_code(ip, old, new);
>> +
>> + /* Also update the regs callback function */
>> + if (IS_ENABLED(CONFIG_DYNAMIC_FTRACE_WITH_REGS) && !ret) {
>> + ip = (unsigned long)(&ftrace_regs_call);
>> + old = ppc_inst_read((u32 *)&ftrace_regs_call);
>> + new = ftrace_call_replace(ip, (unsigned long)func, 1);
>> + ret = ftrace_modify_code(ip, old, new);
>> + }
>> +
>> + return ret;
>> +}
>> +
>> +/*
>> + * Use the default ftrace_modify_all_code, but without
>> + * stop_machine().
>> + */
>> +void arch_ftrace_update_code(int command)
>> +{
>> + ftrace_modify_all_code(command);
>> +}
>> +
>> +#ifdef CONFIG_PPC64
>> +#define PACATOC offsetof(struct paca_struct, kernel_toc)
>> +
>> +extern unsigned int ftrace_tramp_text[], ftrace_tramp_init[];
>> +
>> +void ftrace_free_init_tramp(void)
>> +{
>> + int i;
>> +
>> + for (i = 0; i < NUM_FTRACE_TRAMPS && ftrace_tramps[i]; i++)
>> + if (ftrace_tramps[i] == (unsigned long)ftrace_tramp_init) {
>> + ftrace_tramps[i] = 0;
>> + return;
>> + }
>> +}
>> +
>> +int __init ftrace_dyn_arch_init(void)
>> +{
>> + int i;
>> + unsigned int *tramp[] = { ftrace_tramp_text, ftrace_tramp_init };
>> + u32 stub_insns[] = {
>> + PPC_RAW_LD(_R12, _R13, PACATOC),
>> + PPC_RAW_ADDIS(_R12, _R12, 0),
>> + PPC_RAW_ADDI(_R12, _R12, 0),
>> + PPC_RAW_MTCTR(_R12),
>> + PPC_RAW_BCTR()
>> + };
>> + unsigned long addr;
>> + long reladdr;
>> +
>> + if (IS_ENABLED(CONFIG_DYNAMIC_FTRACE_WITH_REGS))
>> + addr = ppc_global_function_entry((void *)ftrace_regs_caller);
>> + else
>> + addr = ppc_global_function_entry((void *)ftrace_caller);
>> +
>> + reladdr = addr - kernel_toc_addr();
>> +
>> + if (reladdr >= SZ_2G || reladdr < -(long)SZ_2G) {
>> + pr_err("Address of %ps out of range of kernel_toc.\n",
>> + (void *)addr);
>> + return -1;
>> + }
>> +
>> + for (i = 0; i < 2; i++) {
>> + memcpy(tramp[i], stub_insns, sizeof(stub_insns));
>> + tramp[i][1] |= PPC_HA(reladdr);
>> + tramp[i][2] |= PPC_LO(reladdr);
>> + add_ftrace_tramp((unsigned long)tramp[i]);
>> + }
>> +
>> + return 0;
>> +}
>> +#endif
>> +
>> +#ifdef CONFIG_FUNCTION_GRAPH_TRACER
>> +
>> +extern void ftrace_graph_call(void);
>> +extern void ftrace_graph_stub(void);
>> +
>> +static int ftrace_modify_ftrace_graph_caller(bool enable)
>> +{
>> + unsigned long ip = (unsigned long)(&ftrace_graph_call);
>> + unsigned long addr = (unsigned long)(&ftrace_graph_caller);
>> + unsigned long stub = (unsigned long)(&ftrace_graph_stub);
>> + ppc_inst_t old, new;
>> +
>> + if (IS_ENABLED(CONFIG_DYNAMIC_FTRACE_WITH_ARGS))
>> + return 0;
>> +
>> + old = ftrace_call_replace(ip, enable ? stub : addr, 0);
>> + new = ftrace_call_replace(ip, enable ? addr : stub, 0);
>> +
>> + return ftrace_modify_code(ip, old, new);
>> +}
>> +
>> +int ftrace_enable_ftrace_graph_caller(void)
>> +{
>> + return ftrace_modify_ftrace_graph_caller(true);
>> +}
>> +
>> +int ftrace_disable_ftrace_graph_caller(void)
>> +{
>> + return ftrace_modify_ftrace_graph_caller(false);
>> +}
>> +
>> +/*
>> + * Hook the return address and push it in the stack of return addrs
>> + * in current thread info. Return the address we want to divert to.
>> + */
>> +static unsigned long
>> +__prepare_ftrace_return(unsigned long parent, unsigned long ip, unsigned long sp)
>> +{
>> + unsigned long return_hooker;
>> + int bit;
>> +
>> + if (unlikely(ftrace_graph_is_dead()))
>> + goto out;
>> +
>> + if (unlikely(atomic_read(¤t->tracing_graph_pause)))
>> + goto out;
>> +
>> + bit = ftrace_test_recursion_trylock(ip, parent);
>> + if (bit < 0)
>> + goto out;
>> +
>> + return_hooker = ppc_function_entry(return_to_handler);
>> +
>> + if (!function_graph_enter(parent, ip, 0, (unsigned long *)sp))
>> + parent = return_hooker;
>> +
>> + ftrace_test_recursion_unlock(bit);
>> +out:
>> + return parent;
>> +}
>> +
>> +#ifdef CONFIG_DYNAMIC_FTRACE_WITH_ARGS
>> +void ftrace_graph_func(unsigned long ip, unsigned long parent_ip,
>> + struct ftrace_ops *op, struct ftrace_regs *fregs)
>> +{
>> + fregs->regs.link = __prepare_ftrace_return(parent_ip, ip, fregs->regs.gpr[1]);
>> +}
>> +#else
>> +unsigned long prepare_ftrace_return(unsigned long parent, unsigned long ip,
>> + unsigned long sp)
>> +{
>> + return __prepare_ftrace_return(parent, ip, sp);
>> +}
>> +#endif
>> +#endif /* CONFIG_FUNCTION_GRAPH_TRACER */
>> +
>> +#ifdef CONFIG_PPC64_ELF_ABI_V1
>> +char *arch_ftrace_match_adjust(char *str, const char *search)
>> +{
>> + if (str[0] == '.' && search[0] != '.')
>> + return str + 1;
>> + else
>> + return str;
>> +}
>> +#endif /* CONFIG_PPC64_ELF_ABI_V1 */
>> diff --git a/arch/powerpc/tools/gcc-check-fpatchable-function-entry.sh b/arch/powerpc/tools/gcc-check-fpatchable-function-entry.sh
>> new file mode 100755
>> index 00000000000000..410e349cc48428
>> --- /dev/null
>> +++ b/arch/powerpc/tools/gcc-check-fpatchable-function-entry.sh
>> @@ -0,0 +1,20 @@
>> +#!/bin/bash
>> +# SPDX-License-Identifier: GPL-2.0
>> +
>> +set -e
>> +set -o pipefail
>> +
>> +# To debug, uncomment the following line
>> +# set -x
>> +
>> +# Output from -fpatchable-function-entry can only vary on 64le, so this should
>> +# not be invoked for other targets. Therefore we can pass in -m64 and -mabi
>> +# explicitly, to take care of toolchains defaulting to other targets.
>> +
>> +# Test whether the nops are generated before the global entry point.
>> +echo "int x; int func() { return x; }" | \
>> + $* -m64 -mabi=elfv2 -S -x c -O2 -fpatchable-function-entry=2,2 - -o - 2> /dev/null | \
>> + awk 'BEGIN { RS = ";" } /nop\n[[:space:]]*nop\n.*\nfunc:/ { print $0 }' | \
>> + grep -q "func:" || exit 0
>> +
>> +exit 1
>>
>> base-commit: 6d40746dbb75f85a18a0df005f1a8d6147abec22
>> prerequisite-patch-id: 3862cf6dc646260228e50b70c316cf15b1d7f384
>> prerequisite-patch-id: 859f60071f4e425c806fc7fe6c59e268232050a4
>> prerequisite-patch-id: ef23f712e50f106d689a550dae0f816285c1db3b
>> prerequisite-patch-id: 8c6d31bb6ac4e4bef086fe502efa660ae99a96ca
>> --
>> 2.40.1
>>
>
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